JP-7-208661A, JP-7-217779A and JP-2008-57826A describe a fluid passage connecting device having a male component and a female component. The male component has a convex portion, and a seal component such as an O-ring is arranged around an outer circumference of the convex portion. When the male component is combined with the female component to define a fluid passage, a level difference is generated on an inner surface of the fluid passage. Further, a clearance is generated in an axis direction between a tip end of the male component and an inner wall of the female component. The clearance causes fluid turbulence, and the fluid turbulence causes noise.
JP-3936697B2 (US 2004/0178631, U.S. Pat. No. 6,969,094) describes a fluid passage connecting device having a male component and a female component. The male component has a convex portion, and a seal ring is arranged on surface of an axial end part of the convex portion. An inner diameter of the seal ring is approximately the same as that of the convex portion. The seal ring is tightly interposed between the male component and the female component in the axis direction.
In JP-3936697B2, a level difference is restricted from being generated on an inner surface of a fluid passage because the seal ring is arranged to be exposed to the fluid passage. However, the seal ring is arranged not only for the restriction of the level difference but also for achieving sealing property for fluid, so that it is difficult to achieve both of the restriction of the level difference and the sealing property.
Moreover, in order to maintain high sealing property, high dimensional accuracy is required for the male component, the female component and the seal ring.